The primary source of clean, abundant and renewable energy is the sun. One way of utilizing solar energy is the conversion of sunlight into electricity directly using photovoltaics (PV). A solar cell, or photovoltaic cell (PV), is the device that directly converts light into electric current through the photoelectric effect. The solar cell made of semiconductors is the elementary building block of the photovoltaic technology. A number of solar cells electrically connected to each other forms a PV module. Several PV modules can be wired together to form an array. PV modules and arrays are often interconnected in series and/or parallel electrical arrangements to produce any required voltage and current combination. A junction box which allows serial as well as parallel interconnection via direct wire connect or separable connectors, is the placed where the power generated by the solar cells is collected and channelled to the outside. Junction boxes are typically used to electrically connect the PV modules and/or arrays to each other and to an electrical power distribution system. Without a junction box, a PV module and/or an array could not work properly. The junction box is one of the most important components of a solar module and its importance on module quality cannot be underestimated.
Since PV modules and/or arrays as well as junction boxes are generally mounted in a single support structure or frame on a roof, exposed to the outside and severe weather, such as rain or wind, the quality of junction boxes and demands on their manufacture are high. Up to now, there have been two important issues in the field of building a solar photovoltaic junction box assembly, one is to prevent water leaking into the junction box from outside because it may cause a short circuit, and the other is to prevent a cable joined to the junction box from being loosened because it may lead to an open circuit.
In a conventional junction box, gel is applied locally in the junction box to prevent water contacting with electrical connections at the terminals of the electrical connector, and the cable is fixed to the junction box by special fasteners, such as screws, to prevent the cable from being loosened relative to the junction box. However, using special fasteners to fix the cable in a conventional junction box causes the fixing structure of the cable to be complicated and the assembly operation difficult.
As demand for clean energy grows, the above-mentioned fastening method for such junction boxes is further desired, which raises new issues with regards to fastening construction and design. Ever greater significance and attention is given to a tight-sealed fastening of the cable to the junction box despite its sophisticated environment, prevention of water leaking and prevention of cable loosing.